Integral reclosable bag

The invention relates to a plastic bag, the walls of which are constituted by a plastic film and which is provided near its edge, between the opposite internal faces of its walls, of male and female elements, capable of 'be engaged in each other.

As regards the bag itself, it is characterized in that the dimensions and / or shapes of said elements are such that their resistance against their disengagement due to an internal pressure of the bag is a multiple of the force necessary to obtain their engagement or their disengagement by an external action on the edges of the walls of the bag.

As regards the preferred method of manufacturing the bag according to the invention, it is characterized in that the walls of the bag and its closing elements, constituted by a rib and a groove, are obtained in one piece by a process of 'extrusion.

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- 1 333.227

Other advantageous features of the invention will appear during the description given below with reference to the accompanying drawings.

Fig.l of these drawings shows, in section and on a greatly enlarged scale, part of a bag with a rib and groove closure, established in accordance with the invention.

Figs. 2, 3 and 4 show three different embodiments of closure elements in the form of ribs and grooves.

Fig. 5 shows, in perspective, a tubular film provided with a rib and a closing groove, used for the manufacture of bags according to the invention.

Fig. 6 shows the tubular film of fig. 5 flattened, the rib and the groove of the closure being engaged one inside the other.

Fig. 7 shows, in perspective, how individual bags are established from the flattened tubular film of FIG. 6.

Fig. 8 shows, in perspective, a flat film provided with a rib and a closing groove, these ribs and grooves being arranged on either side and near a median line, this film used for the manufacture of bags according to the invention.

Fig. 9 shows the flat film of FIG. 7, folded on itself along its midline, the rib and the closing groove being engaged one inside the other.

uno.

Fig. 10 shows a flat film provided with a ribev, 'closing groove arranged near the edges of the film, which must also be used for the manufacture of bags according to the invention.

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333.227

Fig. 11, finally, shows the flat film of FIG. 9 folded on itself along its midline, the rib and the groove of the closure being engaged one in the lair.

Numerous closures with male and female elements 5 are known for bags whose walls are constituted by a plastic film, but these closures do not take account of the efforts which must be made to open and close the bag from the outside. and the resistance it must oppose to an accidental release of the contents of the bag.

The invention is attached to the establishment of a plastic bag whose walls 1 and 2 are constituted by a plastic film and which is provided near its edge, between the opposite internal faces of its walls 1 and 2, male and female closing elements, elements preferably consisting of a rib and a groove capable of being engaged in one another by a simple pressure between the fingers and which oppose the internal pressure of the content against the sufficient.compte held of the. resistance walls 1 and 2 uno 'rési'sta'ncé / àùù tearing back walls 1 and 2, to safely hold lo contained in the bag and which, however, can be disengaged from each other by a simple pull by fingers on extensions la and 2a of walls 1 and 2 beyond the closure elements (fig- D.

According to the invention, the male and female elements, in this case the rib and the groove of the closure, are given the canvas shapes and / or dimensions as their resistance against their disengagement, due to an internal pressure of the bag. , or several, preferably approximately

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- 3,333,227 five times greater than the force necessary to obtain their engagement or disengagement by an action from the outside on the extensions la and 2a of the walls of the bag.

Advantageously, it is made so that the resistance of the male and female elements of the closure, against their disengagement under the effect of the pressure that the contents of the bag can exert from the inside against the walls 1 and 2, for example in case impact, compression or fall of the bag, either at least equal to, or exceeds, the resistance of walls 1 and 2 to tearing.

The rib ot the groove is given corresponding shapes such that each has, on either side of its axial plane X - Y, perpendicular to the wall 1 t / u 2 of the bag (fig. 2), to which it belongs, different attachment profiles by their shapes and / or dimensions, lo profile which, as a result of this difference, is capable of ensuring the most effective attachment being placed, relative to the plane X - Y, on the side inside the bag.

According to a preferred embodiment, the rib has a head 4 which is secured, by means of a foot 3, to the wall 1 of the bag, and whose asymmetrical shape projecting on either side of the foot 3, opposite wall 1, offers to the complementary edges 5 and 6 of the groove 7 surfaces d, ”attachment of which glue (Ö) which extends from the foot 3 towards the inside of the bag is inclined towards the wall 1 of the bag while that (9) which extends from the foot 3 outward is substantially parallel to said wall.

Advantageously, the rib 3 is given a profile such that in section it has the shape of an asymmetrical arrowhead (fig. 2).

St - 23.6 ^ 62 - 4 333.227

At the groove 7, it is possible to give, between the overhanging edges 5 and 6, a profile which forms an arc of a circle or of an ellipse or part of a polygon.

Advantageously, the groove 7 is provided in a tube 10 which forms a sort of gutter and which, by its bottom 10a, is integral, along its median plane XY, with the wall 2 of the bag, projecting from this wall. towards the rib 3-4 of the other wall 1.

According to a variant, there is provided on each side of the rib 3-4 a strip 11 (fig. 3) capable of pressing the flange 10 against the rib 3-4 ·

According to yet another variant shown in FIG. 4, the groove 7a is formed by the substantially rectangular space, located between two parallel rails 10b and 10c., Integral with the wall 2 of the bag.

Advantageously, the flange 10 (or the rails 10b and 10c.) Comprising the groove 7 (or 7a) is established in the same material as the wall 2 of the bag and in one piece with this wall, and we do do so for the rib 3-4 (and possibly the strips 11) and the wall 1 of the bag.

In this case, advantageously, the walls 1 and 2 of the bag are established and the rib 3-4 as well as the groove 5, 6,

7, 10 in one piece by extrusion,

There are several ways to do this.

Solon a first way, we produce, by extrusion, a tube 12 (fig, 5) and, on the inner wall of this tube, the rib 3-4 ot the flange 10 having the groove 7, the rib and the groove s' extending side by side parallel to the extrusion axis. The tube 12 is flattened by engaging the rib in the groove (Fig. 6). Finally,

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- 5 333.22, the tube 12 is sectioned into sections 12a, 12b, 12ç, 12d, otc .. (fig. 7) which is formed at their ends 13 by welding ot which is then opened above the closure in 14.

In another way, a flat strip 15 (fig. 8) comprising the rib 3-4 and the flange 10 is produced by extrusion, these ribs and flange being arranged on either side of the midline Mj-M₂ of the strip ot near this line. Then we fold the strip on itself along the line M ^ -M₂, ^{in in}S^atS^{being the} rib 3-4 in groove 7 (fig. 9) to, finally, cut out sections which differ from those of fig. 7 by the fact that they are open at 16, on the side opposite to that provided with the closing elements. The opening 16 can be used to fill the bag and then be closed by welding.

According to another variant, it is also possible to provide the rib 3-4 ot the flange 10 with groove 7 parallel and at a short distance from the edges of a flat strip 15a, obtained by extrusion (fig. 10). The strip 15a is then folded on itself, along its midline, and the rib engaged in the groove (fig. 11). We can then cut sections that differ from those in fig. 7 by the fact that they are already open in 14.

It may be advantageous, by proceeding in the manner illustrated in FIGS. 5 to 7 or by figs. Ö and 9, not to open the bag at 14 and to use the wall of the bag, right side, as an additional closure or guarantee strip that must be cut or torn off to gain access to the closing elements properly and the contents of the bag. In this case, it is possible to provide, preferably during the extrusion operation, in the part of the strip 15 (fig. 8) which

St - 23.6.62 _ 6,333,227 extends between the closure elements on the side opposite the bag itself, two weakening grooves 17, located equidistant from the center line of the strip. These two grooves 17 come to overlap when the strip 15 is folded, as shown in FIG. 9 , constituting a preferred tear line to facilitate the tearing of a strip be tween the rib 3-4 and the groove 7 do the closure, which rounds the latter accessible from the outside, as shown in 14 in fig. 11.

It is understood that, when one wants to open the bag by exerting a pull in the opposite direction on the edges la and 2a of the bag in the direction XY (fig. 1), the edges 6 and 9, through which the groove 7 and the rib 3-4 coagulate on the side which, compared to the XY plane, is opposite to the pocket formed by the bag, oppose only a weak resistance.

However, as soon as the edge 9 of the rib has left the groove 7, it is possible, by pivoting the rib in the groove, to easily unhook the edge Ö of the rib from the edge 5 of the groove.

On the other hand, when the content mows to separate from the interior of the bag the walls 1 and 2, the groove and the rib remain firmly anchored in one another by their edges 5 and which penetrate deeply into the other with a strong hooking obliquity, · A hooking, even more solid on th e inside of the bag, is obtained by making the head 4 extend over the foot of the rib more towards the inside of the bag than towards the outside, that is, the excess thickness 4 deviates from the XY plane towards the inside of the bag by a distance

A greater than that of B, of which the same allowance

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- 7 333.227 deviates from the plane X-ï towards the outside of the bag.

In accordance with the shape of the head of the rib, the edge $ which overhangs the groove 7 is given a length greater than that of the edge 6,

When you want to close the bag, you just need to press the outside fingers against the walls 1 ot 2, lo along the plane X-ï, so that the rib 3-4 enters the groove 7, spreading elastically the walls of the rod 10.

When one wants to establish a bag whose walls 1 and 2 are in one piece with the ribs 3-4 and groove 7.10 of the closure device, it is necessary, to obtain optimum resistance qualities, to choose the dimensions of said said rib and groove depending on the thickness of the walls 1 and 2 of the bag.

Indeed, the closure must have the desired qualities of resistance to opening while having dimensions and weight as low as possible.

Assuming that we want to establish the polyethylene bag, we know that a sheet of common quality for packaging has, depending on its thickness, the following qualities of resistance:

25·

<td>: Example no.</td><td> 1</td><td> 2</td><td> 3</td><td> 4</td><td>5 D</td>

<td>: Thickness in mm</td><td> 0,03</td><td> 0,04</td><td> 0,05</td><td> 0,06</td><td> 0,07'</td>

<td>: Tensile strength: kg / 20 cm</td><td> 1</td><td> 1,3</td><td> 1,6</td><td> 2</td><td> 2,35:</td>

<td>: Impact resistance: of a falling weight:</td><td>o0</td><td> 110</td><td> 150</td><td> 200</td><td> 260 :</td>

This table shows that the resistance of the sheet,

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- Ö 333.227 q_ui must constitute the walls 1 and 2 of the bag, ost proportional to its thickness.

It has been found experimentally that the closure must be able to open under a force of 200 g to 800 g (maximum)

It emerges from this that one can then use a polyethylene excavation of only 0.03 mm thick, the resistance of which is 1000 g, as shown in the table above.

Experiments have shown that a closure which opposes a resistance of approximately 2000 g to an unqôuverturo acci10 lace caused by the contents of the bag, and that can be opened or closed at will with the help of an external force of approximately 400 g, suitable for a bag made of a 0.05 mm thick polyethylene sheet, with a tensile strength of 1600 g. In this case, we. obtains a closure whose weight and section are minimum while fully satisfying the user of the bag.

Indeed, the rib 3-4 and lo flange 10 with groove 7 of the closure then weigh about 1.2 g per meter of length ot the distance between the outer faces of the walls 1 © t 2 of the bag at the location of the closure ost of approximately 1.14 mm or 17/15 ram.

The closing rib rib has the following characteristics. Relative to the median plane XY perpendicular to the wall 1, the edge 8 forms an angle ° (from 55 ° to

65 °, the edge 9 an angle β do 00 ° to 90 °, while the soft faces which externally delimit the head of the rib with each make / ί 'axis XY an angle of 35 ° to 45 °. The thickness of the leg 3 of the rib is approximately 5/15 mm ot that of its head 4, at the back of the edges 8 and 9, of approximately 10/15 mm,

The top of the head 4 of the rib is of the wall 1

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- 9 333.227 at a distance of approximately 13/15 mm and from the edge S at approximately 6/15 mm. Lo intersection point back edges 8 ot 9 with the center line XY ost distant from the end of edge 8 by approximately 3/15 mm.

The groove of the formoture has the following characteristics. The thickness of the flange, between the interior wall 7 and the exterior is about 3.3 mm. The spacing ”l5 mm from the edges 5 ot 6 is approximately 7/15 mm, their distance from the bottom of the groove about 8/15 mm,

The dimensions and angles which have been indicated above for the case of a sheet of 0.05 mm thickness (example no. 5) determine the proportions and shapes which are more generally valid. that is to say also for bags whose walls have a different thickness.

The resistance to opening and closing varies proportionally with its weight per meter of length.

We can thus draw up the following table:

<td>Example no.</td><td> 1</td><td> 2</td><td> 3</td><td> 4</td><td> • 5</td>

<td>Weight of closure profiles in g / m</td><td> 0,6</td><td> 0,9</td><td> 1,2</td><td> 1,5</td><td>-co 1-1</td>

<td>Tensile strength in kg / 20 mm / m; interior Exterior :</td><td> 1 0,2</td><td> 1,5 0,3</td><td> 2 0,4</td><td> 2,5 0,5</td><td>3 î 0.6:</td>

In this table, the term '' interior refers to the interior parts, ot the term exterior to the exterior parts of the bag. We can consider the values ​​indicated as being those which represent the maximum effort required to cause the opening of the bag, either from the inside or from the outside, i.e. to separate one of the 'other

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- 10 333.227 either edges 8 and 5, or edges 9 and 6 (fig. 2), by a pull acting on the walls 1 and 2 of the bag (fig. 1) in the opposite direction, either below or above the XY plane (see the situation of this plane in fig. 1).

Advantageously, the closure elements indicated in the second table and designated by the same example numbers are used for the sheet thicknesses indicated in the first table and designated in by different example numbers. Thus, it is possible to use a closure according to Example 1, having a weight of 0.6 g / m, with a polyethylene sheet according to Example 1, having a thickness of 0.03 mm. In the combinations thus proposed, the closure has sufficient hold while remaining a minimum weight for a determined thickness of sheet.

1 $ polyethylene and you can be sure that the proportion between the external resistance and the internal resistance is approximately 1: 5.

The bag according to the invention could, of course, be made with a closure device, the male and female elements of which have shapes different from those of the rib and groove recommended and shown in the drawings, provided that the closure device opposes at the opening a resistance several times greater from the inside than from the outside, the resistance of the walls of the bag in front of you greater than the latter but preferably being less than the former.